Re: [BUG] Odd interaction between uninterruptible syscall and stack overflow

Linus Torvalds
2015-03-15T22:19:15Z

On Sun, Mar 15, 2015 at 11:12 AM, Simonas <s@kazlauskas.me> wrote:
> While working on stack related code in Rust’s stdandard library, I trigerred
> a very odd and amusing issue yesterday.

This sounds like a the subtle backporting issue we had where a subtle
semantic dependency was missed, and as a result 3.18.6 was buggered
for the case of a stack overflow.

Basically, commit 33692f27597f got backported without commit
7fb08eca45270d, and broke. Normally these dependencies are obvious and
cause the patches to not apply at all, or the result to not work in
obvious ways, but in this case the stable trees were unlucky, and the
patch applied cleanly and everything normal seems to work, but then
stack overflows end up not releasing a semaphore.

It should be fixed in 3.18.7 already, but clearly a few distributions
were unlucky and hit the broken kernel.

Linus